A central issue for interventional surgical procedures remains visualization of the unexposed anatomy and localization of medical devices within the organs and vessels, such as catheters, stents, probes, and the like. As procedures move away from maximal exposure towards being minimally invasive, the requirements for enhanced visualization are more profound. An example is minimally invasive transcatheter ablation for cardiac arrhythmias.
In healthy hearts, organized electrical excitation causes heart contraction. When this electrical activity becomes irregular, the heart can no longer pump efficiently and patients experience dizziness, fainting, and/or sudden death. Statistics from the Centers for Disease Control and Prevention have estimated that in the United States sudden cardiac death claims more than 600,000 victims every year. Erratic, irregular electrical cardiac activity is called an arrhythmia, and is often caused by abnormal electrical connections in the heart. Cardiac arrhythmias affect people of all ages.
These short circuits can be effectively removed by applying one or more energy pulses to a selected region of the heart through a catheter that is placed in the heart, known as a transcatheter ablation. Non-limiting examples of types of energy pulses that may be applied using a transcatheter ablation include radiofrequency energy pulses, cryoenergy pulses, and high frequency ultrasound pulses. A mainstay of modern arrhythmia therapy, ablation procedures require multiple catheters to be inserted into the heart to record electrical activity, identify key locations responsible for the arrhythmia, and ablate tissue using either radiofrequency energy or cryotherapy. Currently, ablation procedures are complicated by the masking of the heart by the chest wall and separation of data (i.e., electrical signals, anatomic location, etc.) in the electrophysiology laboratory, requiring the physician to mentally reconstruct a heart model.
These procedures have been enhanced significantly by the development of electroanatomic mapping systems that construct a point-by-point map of the interior surface of the heart (endocardium) incorporating both anatomic location and the local electrical signal. However, these systems are limited by the display of key measurements on multiple two-dimensional screens. The skill to mentally relate electrical recordings to the overall multi-dimensional cardiac anatomy remains a key challenge in the training of cardiac electrophysiologists and intra-procedural collaboration. It is therefore intensely difficult to train new physicians, and significant skill-dependent variability in outcomes is common.